SQOTD: Changing Alignment Stationing

QUESTION:

In C3D, I have an alignment for a road in a park that creates a closed

loop. When I turn the polyline into an alignment, it seems to randomly

select the starting point for the alignment. I want to change the

default location it is choosing for the beginning of the alignment - in

alignment properties I see that I can modify the reference points

stationing, but it won't allow me to change the stationing for the

starting point of the alignment. How can I do this?

ANSWER:

When you are first converting a polyline into an Alignment, the end nearest to which you click becomes the 0+00 station. (In the case of a closed loop, the vertex closest to where you pick becomes 0+00) If you don't want it to be 0+00 you can set it on the same window where you give it a name.

BUT if you forget you can still change it.

If you just want to flip-flop the

alignment end-to-end you can go up to the Alignments menu and select Reverse Alignment Direction.

If you want to change the start station of the alignment to be

something other than 0+00, jump into the Alignment properties.

Left-click, then right-click on the Alignment (or right-click on

its name in Prospector)and select Alignment Properties. Go to the Station Control tab.

First, type in the Station where you really want it to start. Second, click the pick-in-cad button next to the X and Y cords.

Civil 3D will throw a warning message at you telling you that you are about to wipe out any station equations you might have entered and anything referencing that alignment will need to be updated. Just say OK and it should pop you into CAD with a special station-picker tool. Use your object snaps to re-snap to the beginning of the alignment, then hit enter. Back at the Alignment properties window, click Apply and you should see your station information update.

And that’s it!

Let me know how it goes.

Louisa